Introduction. 
The successful observation of gravitational-wave (GW) signal from compact binary coalescence [1]} by Advanced LIGO [2]} and Advanced Virgo [3]} has open up a new era of GW astronomy. The superposition of a large number of not loud enough GW incidences can produce a stochastic gravitational-wave background (SGWB) which encodes information about the physics of astrophysical sources. Until the O3 observing period, the LIGO and Virgo Scientific Collaboration has not detected such a SGWB, and therefore they set the upper limits of SGWB [4]}.
